Well, let's face it. Voyager is not your father's Star Trek, but I'll try to give an unbiased review:
In some ways she reminds me of Captain Picard, but without the coolness factor. As you'll recall, Picard was a diplomat at heart; many of his assignments were to settle some dispute, which he always somehow managed to handle extremely well. Similarly, Janeway always tries to weasel out of confrontations by negotiating. Which isn't a bad way to be, but...
The difference is, Janeway rarely does anything admirable except follow her Starfleet principles, even while stranded in the Delta Quadrant. Picard respected the rules of Starfleet, and the Prime Directive, without letting them get in the way of what was right. Recall the incident in which he saved Wesley Crusher's life, going against the PD. Of course, some may argue that he should've let Wesley burn in hell, but I'll leave that for you to decide. There have been several other occasions on which Picard has disobeyed orders for the greater good - the movie Star Trek: Insurrection comes to mind.
Meanwhile, Janeway refuses to do anything to help her crew get home faster. Her insistence on following protocol has caused numerous setbacks in Voyager's trip home, although it's hard to judge whether some of her decisions were ethically correct or not.
For example, in Caretaker (VOY), the series premiere, she destroyed the Caretaker's array in order to protect the Ocampa. Unfortunately, that decision left her ship stranded. Had she not destroyed the array, it is highly likely that they could have deduced how to use it to send themselves back home. On the other hand, was it worth sacrificing the lives of the Ocampa? Perhaps not. But hey, we all know what Kirk would've done - screw the Ocampa! At least they'd be home by now, and we wouldn't have have had to suffer the past seven years.
Okay, so I've been harsh. The truth is, depending on your viewpoint, Janeway is either the biggest problem with the series or its greatest asset. As annoying as she can be, I haven't made a final decision.
I like this character, if only because she's actually had some character development (albiet very little). Yes, she was brought on as a marketing ploy, but her presence has truly made watching the show more interesting and enjoyable.
At first, I was happy that we were seeing more of the Borg, and the stuff with Species 8472 was pretty interesting. But what it boils down to, is that the Borg aren't scary anymore. Bummer. Can you believe that the biggest threat Voyager has seen this season was the Ferengi? Wow, I feel bad for the Ferengi. They deserve better.
You know what? The Doctor is probably the best character on the show. He practically makes it worth watching; perhaps they should rename it Star Trek: The Doctor and Seven of Nine. He's the only character to have some REAL character development - and he's a HOLOGRAM!
Maybe we'd be better off if they just blew up the damn holodeck. Let's face it; holodeck gone haywire stories are trite and overdone. It was cute in The Big Goodbye (TNG) and Elementary, Dear Data (TNG) but now it's just old. Or maybe the Bynars could take out the go_haywire() function they put in so that they could laugh at the silly humans getting killed by holograms. Just a thought. Fair Haven, anyone?
In spite of all this, I do enjoy watching Voyager. I don't agree that it's one of the best Star Trek series; in fact, I think it's most certainly the worst. But for all the horrible garbage it has produced, there have been a few good episodes. The tale of Seven of Nine's lost love was questionable but still a tear-jerker, if you're into the Borg romance thing. The episode where the ship became trapped above a fast-moving planet was truly fascinating. And the recent two-parter about the rights of holograms was slow-moving (and should've taken only an hour) but ultimately quite thought-provoking. It's too bad they had to ruin it at the end with the old "we can't decide the best way to solve this so let's throw in a monkey wrench that makes the choice obvious" ending. I hate that.
Sorry for the rambling aspects of some of this review; I may very well clean it up a bit. Overall, this show has gotten better and better each season, and the finale is definitely something to look forward to.
Update:
The finale was yet another example of Voyager's cheap plot devices: time travel. While the ending was certainly satisfying (as described by BelDion's writeup below), I do wish they could have found a less contrived solution. For example, instead of having Future Janeway tell them about the Borg transwarp nexus, they simply could have discovered it themselves. No time travel needed!